Merge pull request neetcode-gh#2980 from rohankayan/main

Create: 0473-matchsticks-to-square.java

java/0473-matchsticks-to-square.java

@@ -0,0 +1,40 @@
+class Solution {
+ boolean[] used;
+ public boolean makesquare(int[] matchsticks) {
+ used = new boolean[matchsticks.length];
+ int total = 0;
+ for (int n : matchsticks) {
+ total += n;
+ }
+ //Check if total of all the sides is divisible by 4 or not
+ if (total % 4 != 0) return false;
+ int side = total / 4;
+
+ return helper(matchsticks, side, 0, 0, 4);
+ }
+
+ boolean helper(int[] matchsticks, int targetSide, int currentSum, int index, int sides) {
+ //if all the sides are matching the target side length then we found a solution
+ if (sides == 0)
+ return true;
+ //Check if current side is equal to targetSide , that means we found another side
+ if (currentSum == targetSide) {
+ return helper(matchsticks, targetSide, 0, 0, sides - 1);
+ }
+
+ for (int i = index; i < matchsticks.length; i++) {
+ //Only use matchsticks which are not used and which doesn't increase the current side more than target side
+ if (!used[i] && currentSum + matchsticks[i] <= targetSide) {
+ used[i] = true;
+ boolean found = helper(matchsticks, targetSide, currentSum + matchsticks[i], i + 1, sides);
+ if (found) {
+ return true;
+ }
+ used[i] = false;
+ }
+ }
+ return false;
+ }
+
+
+}